1. Field of the Invention
This invention relates to a pregrouted baseplate for supporting rotating machinery commonly used in industrial processing and the method of its use and manufacture. This rotating machinery usually takes the form of pumps, commonly referred to as driven equipment, that is powered by electric motors or steam turbines, commonly referred to as drivers.
Typically, industrial processing plants use large quantities of pumps for moving materials, usually in a liquid or gaseous form, through the processing procedures. These pumps are powered by electric motors or steam turbines as noted above that are mounted adjacent to the pump and coupled thereto by drive couplings. These drive couplings allow for a small amount of misalignment between the output or driving shaft of the drivers, i.e., electric motor or steam turbine, and the input or driven shaft of the driven equipment. Precise alignment between these shafts is critical for the pump and motor assemblies to have a reasonable service life. A critical aspect of maintaining this precise alignment is that the pump and motor are mounted to a mounting base or baseplate as they are commonly referred to in the industry.
These baseplates have mounting pads or surfaces that are precisely machined to help ensure proper alignment between the pump and motor shafts discussed above. The mounting surfaces include threaded holes machined to accept mounting bolts that secure the pump and electric motor to the baseplate. The baseplates are then prepared for installation on a foundation in the plant. It is this preparation process that causes problems with the baseplates.
The aforementioned baseplates typically have been a substantially rectangular parallelepiped configuration with one of the large sides missing to form an open box. The interior of this box forms a large cavity that has been the bottom side of the baseplate with the mounting surfaces previously described formed on the top side. In order to add stiffness to the baseplate and reduce vibration from the pump and motor operation, the cavity on the bottom of the baseplate was filled with a grout material such as epoxy or a cementitious material. The baseplate was then installed on a foundation in the plant and the motor and pump reattached. The problem with such a procedure is that the baseplate thus formed was distorted by the shrinkage of the grout material and the aforementioned precisely machined mounting surfaces were often out of tolerance. This resulted in increased vibration of the pump and motor assembly during operation and a shortened service life. The typical solution to date has been to try to remachine the mounting surfaces of the baseplate after the baseplate is installed on the foundation. This has produced less than desirable results as the machines used in the field cannot produce the desired tolerances and the cost of transporting and setting up these machines is prohibitive.
Therefore, there exists a need for a baseplate and the method of its use that will allow the use of epoxy or cementitious grouts while maintaining the required tolerances for the pump and motor mounting surfaces after installation. It is the construction and method of use of such a baseplate to which the present invention is directed.
2. Description of Related Art
U.S. Pat. No. 2,916,233 to M. F. Ecker discloses a pump base that is grouted in place.
A machinery base pad for vibrating machinery is disclosed in U.S. Pat. No. 5,149,050 to D. Smith et al. A plurality of channels and drains are provided to minimize environmental pollution from the lubricants vibrated out of the machine.
U. S. Pat. No. 5,277,395 to D. Smith et al. is a continuation of U.S. Pat. No. 5,149,050 and describes a machinery base pad with a plurality of I beams and tie down fastener subassemblies with a cementitious filler.
The pregrouted base plate of the present invention and the method of its use and construction is designed for use with rotating machinery such as pump and electric motor assemblies that are coupled together by a pair of shafts and require precise alignment of those shafts for a long and dependable service life. The pregrouted base plate is formed as a generally rectangular parallelepiped structure of suitably thick steel with one side open. The closed or top side of the pregrouted baseplate has a plurality of machined surfaces to which the pump and motor assemble will be bolted. This top surface may have a plurality of vent and grout holes formed therein also. The bottom or open side of the baseplate forms a large cavity into which the grouting material will be poured. This cavity may also have a number of stiffening members or ribs welded in place to minimize distortion of the baseplate. In a typical application of the novel method, the baseplate has the pump and motor assembly removed therefrom and the baseplate is inverted, i.e., the lower cavity is facing upward. If the baseplate has any vent or grout holes as mentioned previously, these are closed off. The surface of the baseplate that will be in contact with the grout material is prepared and cleaned by suitable means as sanding, sandblasting or solvent cleaning to ensure proper adhesion with the grout material. The grout material, either epoxy or cementitious, is prepared and poured into the cavity. The grout material is then allowed to cure. In the case of cementitious grout,. this can be up to five days. If epoxy grout is used and it is desired to accelerate the curing process, the baseplate with grout in place is postcured by maintaining an elevated temperature for a specified time period according to the grout manufacturer""s instructions.
After the grouting material is completely cured, the baseplate is then placed on a table such as that of a horizontal boring mill and secured thereto. The mounting surfaces of the top of the baseplate are then checked for specified tolerances for levelness and flatness. The horizontal boring mill is then used to machine the mounting surfaces as required to bring the mounting surfaces into tolerance. Thus, a pregrouted baseplate is formed with the required grout material in position, properly cured and the mounting surfaces for the pump and motor assembly machined within tolerance. The pregrouted baseplate can then be installed on a foundation in the conventional manner.
One object of the present invention is to provide a method for producing a pregrouted baseplate that ensures the mounting surfaces for the pump and motor assembly are within tolerance after the grouting material is installed and cured.
Another object of the present invention is to provide a baseplate with a grouting material previously installed that is distortion free.
A further object of the present invention is to produce a baseplate free of air pockets or voids in the grout material.
Other objects and advantages of the present invention are pointed out in the claims annexed hereto and form a part of this disclosure. A full and complete understanding of the invention may be had by reference to the accompanying drawings and description of the preferred embodiments.